One type of conventional cloth guide mechanism for use in sewing machines comprises guide means disposed at an angle to a line intersecting the direction in which a piece of cloth to be sewn is pulled and adapted to fold the cloth at one side edge thereof, the guide means being provided with a slanted portion; and control means for controlling the movement of the cloth as the same moves along the slanted portion of the guide means so as to maintain the distance of a seam line to be formed in the cloth from the folded side edge at a constant value. However, in such a prior art cloth guide mechanism the cloth is forced to move along the slanted portion of the guide means and the folded side edge of the cloth is strongly urged against the control means. Furthermore, when the cloth has a lappet of a constant width formed by being folded at one side edge of the cloth, the lappet does not directly contact the guide means as the cloth moves around the slanted portion of the guide means, but only the remaining wider portion of the cloth directly contacts the periphery of the guide means. This causes a frictional resistance, and therefore, the area of the cloth portion which contacts the slanted portion of the guide means as the cloth is pulled is larger than that of the lappet having the constant width and as a result, the lappet which should have a predetermined constant width is strongly urged against the control means and a larger percent of the remaining wider portion of the cloth is caused to be displaced toward and strongly abutted against the control means, whereby the folded side edge will become out of shape resulting in a variation in the distance of the seam line in the cloth from the folded side edge. Such variation in the seam line distance will produce an inferior quality cloth product having a meandering seam line therein. And the folded side edge of the cloth will become out-of-shape as the cloth is pulled while being strongly urged against the control means, and if the cloth having the out-of-shape edge fold is continuously pulled along the guide means the out-of-shape edge fold may overlap over another portion of the cloth which may underlie the lappet to increase the thickness at the area where the seam line is to be formed to the extent that the thickened cloth portion clogs the guide means, thereby makeing it impossible to pull the cloth through the guide means and resulting in obstruction of the formation of any seam line in the cloth.